1. Field of the Invention
The invention relates to tire pressure monitoring sensors for vehicles and specifically to universal tire pressure monitoring sensors which are adaptable to a variety of vehicles and a variety of sensor hardware platforms.
2. Description of Related Art
A tire-pressure monitoring system (TPMS) is an electronic system for monitoring the air pressure inside a pneumatic tire on various types of vehicles. A TPMS reports in near real-time tire-pressure information to the vehicle's control system and to the driver. The TPMS mentioned herein are direct TPMS, which are mounted inside a tire and have at least one wheel sensor (herein called sensor) for measuring the pressure in the tire.
TPMS sensors may be installed by vehicle manufacturers as OEM (Original Equipment Manufacturers) products or they may be installed in workshops for replacement or refurbishment purposes as an after-market (AM) solution. Most car manufacturers use sensors employing a specific protocol to transmit data to a specialized receiver in the vehicle. Furthermore, the sensors may operate differently, for example by transitioning between different modes during their operation, depending on a vehicle manufacturer, model, year of production, make and TPMS manufacturer. These differences influence implementation of the TPMS sensors, that is: triggering conditions for an internal program flow, learning algorithms, timing, communication protocol behavior, data packet content, etc.
In order for a single TPMS sensor to cover most of the TPMS sensor aftermarket (AM) all relevant modes must be supported by the respective AM-TPMS sensor implementation(s). In order to accomplish this goal, one may either implement a multitude of sensor types, each implementing a fixed set of modes, or a universal sensor, which can be either used on all relevant existing vehicles directly, or which can be programmed/modified by installers to support one or more modes. Using a multitude of sensor types is not desirable, as it requires the sensor installers to have a multitude of TPMS sensors on stock. This results in a high initial investment for the installer and the supply chain and makes the sensor selection time consuming. A universal sensor seems to be a much more economical solution.
US 2014/0165026 A1 discloses a method, systems and tools for programming tire pressure monitoring sensors. Vehicle identification information is used to select a suitable program software for the sensor from a database. This is very flexible as new program implementations can be added later to the database. As the full software has to be loaded to the sensor, the programming times are comparatively long, as a low speed communication interface is used. This interface is normally used for transmitting sensor specific data and triggers by the sensor installers. Furthermore, the intense communication would reduce the capacity of the battery built into the sensor. Alternatively, a wired interface may be used. Such a wired interface requires additional hardware like drivers and electrical contacts, which make the sensor susceptible to ESD damage and corrosion at the electrical contact points. The handling of a wired interface is more complex as a cable has to be connected to the sensor prior to programming and disconnected after programming.
US 2009/0033478 A1 discloses a universal tire pressure monitoring sensor. A plurality of selectable programs is stored in the sensor and for adapting the sensor to a specific vehicle, the required program is selected. This allows for a very fast programming, as the correct program has to be only selected. The drawback of this solution is that a large number of programs have to be stored in the sensor which further requires a large overhead of memory, increasing the sensors costs. Alternatively, the memory-limited microcontroller of the TPMS sensor may only be pre-configured for a selection of vehicle models or protocols, which would require to keep a large number of sensors on stock to provide AM coverage. A further disadvantage is that, due to pre-stored programs, no adaption to future requirements is possible. Instead, new sensors have to be developed.
EP 2821260 A1 discloses a method for setting a TPMS sensor by deleting unnecessary encoding procedures. As initially a large number of encoding procedures has to be stored in memory, a comparatively large memory is required or the memory limitation of commercial micro-controllers forces a number of sensors to be stocked which further increases the costs of the sensor. Finally, adaption to new cars is not always possible, unless they fit into an existing scheme. Otherwise a new sensor has to be released.
All the above-mentioned prior art relies on an external programming tool used by the AM installer to modify a sensor by the means of wired or wireless communication. Such a programming tool may have to be modified each time a new revision of sensor hardware platform is released, depending on the implementation of the prior art. For example if a processing unit, antenna, on-board sensor, communication protocol integrated circuit (IC) or other electronic or mechanic component is modified for the sake of price optimization, component production discontinuation, bug fixing, functional improvements, etc.
For that reason modifying a sensor hardware platform requires introduction of new version number of the sensor, thus affecting other parties involved in the sensor after market. Installers, middle-men and sensor producers are affected by a necessity to store a multitude of versions of the sensors. The programming tool producers must be involved by the sensor producers to include the new version of the program. All the parties are affected by extra complexity. Accordingly, sensor versioning results in extra costs, greater handling complexity, time slips and return rates.
These drawbacks discourage the TPMS sensor producers from modifying the hardware platform of the sensors at the pace of technological advances. This results in low dynamics of the sensor market, greater costs of the sensors and lower functional and user safety.
None of the above-mentioned prior art addresses this problem directly.